By definition, urbanization comprises population immigration to an already existing urban area that results in expansion of that area at the cost of rural or natural land. Thus, surrounding outskirts will be changed from rural to urban.
Urbanization occurred primarily due to economical changes within both rural and urban areas. As agriculture become more technologically advanced, there was less need for people to do work that could now be replaced by machines. In addition, living in rural areas and working on farms oftentimes also became unpredictable during times of flood, drought, or pestilence. Urban areas, in turn offered greater occupational opportunities that rural areas simply did not posses (historically job opportunities allowed workers to earn more money and to send some money back to family members in rural areas). Moving closer to urban areas also allowed for a reduction in travel/commuting time or expenses that often resulted from having to work in an urban area but residing outside urban perimeters. Urban centers also offered increased educational opportunities, housing, and transportation. The urban areas often contain better services (medical, social). Many individuals also found it necessary to move closer to urban areas, due to better availability of medical professionals, especially specialists in a certain field of medicine. Greater availability and variety of entertainment sources, such as restaurants, theaters, night clubs, or recreational places have also played a role in people’s decisions to move to a urban area.
Urbanization has effected increased density in affected areas, most notably in growing cities, and is oftentimes accompanied by a multitude of problems or consequences.
One of these problems is sprawling. Some problems associated with development that proceeds over the countryside, also termed sprawling development, include a less desirable or less stable land use pattern, since sprawling does not allow for extensive planning of land use. Further, the land use pattern becomes more costly to develop and service and higher costs are associated with land and energy resources. There would be great costs for providing public services and it would be necessary to extend services to less populated to almost vacant areas. There would also be a higher disruption of agricultural uses. In addition, there would likely be conflicting interests in terms of land use for rural or urban purposes. Loss of farm and forest land would have a negative impact on the agricultural industry (http://www.co.marion.or.us/NR/rdonlyres/0E0F5E36-9AAD-4610-A94A-96D44A819D35/12844/Urbanization.pdf).
Another problem that arises from urbanization is the noted rise in respiratory problems in individuals living in or in close proximity to urban areas. Factors, such as industrial or vehicular emissions, especially those related to combustion, industrial activities, mining, or drilling tend to be responsible for greater levels of toxins in the air. It has been presumed that global warming (and consequent climate change) is one resulting problem from increased urbanization. There has also been poorer air quality noted in buildings and households within urban areas due to air conditions outside, as well as building materials and household products. As a result, respiratory infections may occur from excessive exposure to oxides of nitrogen, which in turn can decrease lung function (http://www.medindia.net/news/healthwatch/Urbanization-And-Rising-Respiratory-Problems-28641-1.htm).
The population density resulting from urbanization has further been attributed to rising crime rates in urban areas. This observation may be due to greater variations in the composition of the population residing in urban areas, especially since a higher number of youths tend to reside in close proximity. Other factors that may be related to higher crime rates are cultural and educational factors. Generally, the higher the level of education within an area, the lower the crime rate. What economic conditions are like in urban areas also determines the likelihood of resulting criminal incidents. For instance, factors such as median income, availability of jobs, or poverty level are good predictors of impending crime. Similarly, family composition and conditions (such as divorce, single parenthood) may also relate to crime rates (http://www.fbi.gov/ucr/05cius/about/variables_affecting_crime.html).

Migration of people from rural area is resulting into urbanization . Industries due to access to markets are putting up factories near urban areas which results into industralisation of that particular area .Worker blue as well as white collars starts residing in near by areas hence resulting in urbanization .

This has resulted in huge presssures on civic bodies of cities and town . Rural areas lag behind the amenities as local bodies are more focussed on urban areas . Divides of have and have nots has increased so has the crime s.